Tractor mounted loader



Feb. 10; 1970 4 B. P. ALDERMAN ET AL M 3,494,495

TRACTOR MOUNTED LOADER Filed Nov. 24, 1967 5Sheets-Shet l F'G.l

INVENTORS 355f ffi JAMAS' 4. ovrwaaa BY Wan/Mr J. law/Mo ATTORNEY Feb. 10, 1970 B. P. ALDERMAN, E 3,494,495

TRACTOR MOUNTED LOADER '7 Filed Nov. 24, 1967 s Sheets-Sheet 5 INVENTORS 5088) nzafiemnn/ JAMIS A. (147N000 ATTORNEY United States Patent 3,494,495 TRACTOR MOUNTED LOADER Bobby P. Alderman, Royal Oak, Mich., Habil S. Basrai, Stillwater, Okla., and James A. Caywood, Birmingham, and William J. Howard, Warren, Mich., assignors to Ford Motor Company, Dearborn, Mich., a corporation of Delaware Filed Nov. 24, 1967, Ser. No. 685,629 Int. Cl. E021? 3/70, 3/87 US. Cl. 214-762 4 Claims ABSTRACT OF THE DISCLOSURE This invention relates to automatic contro s for tractormounted loaders.

Tractors of the off-highway type, including industrial and general purpose tractors, often are provided with front-mounted loaders comprising a forwardly extending boom mounted for vertical swinging movement on the tractor and carrying a tiltable bucket extending transversely in front of the tractor. The bucket is loaded by lowering the boom and driving into a pile of material with the bucket in forwardly-opening position to force material into the bucket.

The bucket is curled (open side tilted upward) and raised a few feet, after which the tractor may be driven to a waiting dump truck or pile where the material is to be deposited. By raising the boom and rotating the bucket to dump position, the material is unloaded, after which the cycle is repeated.

The present invention is directed to improved manually operated and automatic controls for the hydraulic circuits for raising and lowering the boom, and tilting the bucket.

According to the present invention, a manually operated sequential valve of the distributor type operates the control system to select between completely manual control of the loader, automatic positioning of the boom and bucket for loading and raising to transport height, automatic control for raising the boom and bucket to dump position, automatic control for dumping position, and automatic control for relowering the boom and positioning the bucket for reloading. The operator may manually select the several positions of the sequential valve and at any time may manually override the automatic controls of the loader boom and bucket.

In one form of the invention, during the load cycle the automatic controls sense the torque loading on the tractor drive mechanism and automatically initiate raising of the bucket after tractor drive line torque has reached a predetermined amount as the bucket is forced into the load of material.

Among the objects of the present invention are to provide an improved control system for tractor-mounted loaders in which bucket curl and dumping is automatically controlled in accordance with load and position requirements; to provide such controls in which overload of the loader hydraulic system is prevented; to provide a control system which may be manually operated by a single sequential valve; to provide such a system in which the loader conice trol may be manually overriden at any time; to provide such a system in which the tractor drive line torque supplied by the engine is limited when loading the bucket; and generally to improve loader controls of the type described.

Other objects and objects relating to details of construction will be apparent from the detailed description to follow.

FIGURE 1 is a side elevation of a tractor and front mounted loader with which the present invention is intended to be utilized, only the forward portion of the tractor being shown.

FIGURE 2 is a schematic diagram of the hydraulic control system for operating the lift cylinders and bucket cylinders of the loader.

FIGURE 3 is a schematic diagram of the hydraulic control system for automatically operating the lift cylinder and bucket cylinder control valves shown in FIGURE 2.

FIGURE 4 is a schematic diagram of a modified form of hydraulic control system for operating the lift cylinder and bucket cylinder control valves of FIGURE 2, the controls being modulated by drive line torque of the tractor when loading the bucket.

FIGURE 5 is a somewhat diagrammatic elevation of portions of the loader frame, boom and bucket, showing cams and cam operated valves for sensing position of the boom and bucket and controlling operation of the loader.

FIGURE 6 is a view similar to FIGURE 5, showing cams and cam operated valves for sensing boom position and controlling operation of the loader.

Referring to FIGURE 1, the tractor 10 is an industrial model four-wheel tractor which is provided with a loader mounting frame including an upright frame portion 11 at each side of the tractor and intermediate the front and rear wheels, one upright frame portion 11 being shown. A loader boom 12 comprises a pair of side rails pivotally mounted on the tops of the upright frame portions, one side rail 14 being shown. The side rails 14 are mounted for vertical swinging movement and extend one on each side of the tractor hood portion 15, extending forwardly and downwardly and terminating a short distance in front of the tractor. A pair of double-acting cylinders extend between the frame portions 11 and the side rails 14, one cylinder 16 being shown. Extending the cylinders serves to raise the loader boom 12 about its pivotal connection to the upright frame portions 11 and retraction of the cylinders serves to lower the boom.

A loader bucket 17 is pivotally mounted for vertical swinging movement on the front ends of the side rails 14. The bucket 17, which is generally conventional, is forwardly opening and has a generally flat bottom wall 19. The other walls of the bucket preferably also are flat, having the general contour indicated in the drawings.

A pair of double-acting bucket cylinders 20- extend between an abutment 21 on the loader boom and a bucket operating linkage consists of the articulated links 22 and 24, extension of the cylinders 20 rotating the bucket counterclockwise on the boom 12 as viewed in FIGURE 1 and retraction of the cylinders rotating the bucket clockwise. The loader construction described immediately above is more or less conventional and does not form a part of the present invention.

Referring now to FIGURE 2, the hydraulic system for operating the cylinders 16 and 20 of the loader comprises a pump 25 which preferably is driven from the tractor engine, customarily being mounted at the forward end of the engine and driven directly from the forward end of the crankshaft. The pump 25 may be a fixed displacement pump.

As indicated in FIGURE 2, the pressure line 26 extending from the pump 25 leads to a lift cylinder control valve 27 and a bucket cylinder control valve 29, the two valves being connected in parallel so that either valve may be operated independently of the other. Both valves preferably are of the open-center type.

Both of these valves are three position spool type valves of the type indicated in the drawings and may be operated both hydraulically and manually. The valves are spring-centered, open-center valves. When neither valve is operated, the flow from the pressure line 26 is passed to sump.

The lift cylinder control valve is connected with the lift cylinders by lines and 31, operation of the valve 27 in one direction extending the lift cylinders 16 so as to raise the loader boom 12 and operation of the valve in the other direction serving to retract the cylinders and lower the boom. In neutral position of the valve (shown in the drawings), oil is trapped in the lift cylinders and the boom is held stationary.

The bucket cylinders 20 are similarly connected with the bucket cylinder control valve 29 by lines 32 and 34, operation of the valve 29 in one direction serving to extend the bucket cylinders 20 to move the bucket toward dump position and retraction of the cylinders 20 serving to curl the bucket (raise the open forward side of the bucket). In the neutral position of the valve 29, oil is trapped in the cylinders 20* and the bucket is held stationary relative to the boom.

A relief valve 35 connected with the pressure line 26 serves to relieve pressure in the system should it exceed a predetermined amount. The relief valve 35 may be set for 1800 p.s.i.

Automatic operation of the control valves 27 and 29 is controlled by the valve control system shown in FIGURES 3 and 4.

Referring now to FIGURE 3, a sequential valve 36 is provided for manual operation by the tractor operator. The sequential valve 36 is of the distributor type and is supplied with pressurized hydraulic fluid from the pressure line 26 by means of a line 37. A pressure reducing valve 39 in the line 37 reduces pressure supplied to the control circuits to about 300 p.s.i.

The sequential valve 36 is of the distributor type to supply pressure to either of four hydraulic circuits leading from the valve 36 to control cycling of the loader as will be described or in manual position to block passage of pressurized fluid to any of the lines, thus permitting the automatic control circuits to be inactivated and the loader operated manually in the customary manner by the valves 27 and 29.

LOAD POSITION The sequential valve 36 is shown positioned to direct fluid to the line 40 for activating the bucket load cycle of the loader. The line 40 extends to a detented valve 41 which is normally closed. The line 42 leading from the valve 41 extends to a bucket curl control valve 44 which in its normal position extends to communicate through line 45 to the bucket cylinder control valve 29. Automatic operation of this circuit is controlled by pressure in the lift cylinder line 30 which is a function of effort required to lift the loader boom and bucket. This pressure communicates through line 46 to the valve 41 for operating the valve against its spring bias. The bias is adjustable to regulate the pressure required to operate the valve 41.

In the load position, the bottom wall of the bucket previously has been positioned parallel to and just above the ground as will be explained hereinafter in connection with the return to load cycle. The tractor with the bucket and boom so positioned is driven forwardly into a pile of loose material to load the bucket. As the bucket is loaded, the manual control of the lift cylinder control valve is actuated in the direction to lift the boom. Upon pressure in the line 30 exceeding the pressure required to operate the valve 41, which is below the pressure required to blow the relief valve 35, the valve 41 is operated to open the passage through line 42, valve 44, and line 45 to operate the bucket cylinder control valve 29 in a direction to curl the bucket and relieve the load in the lift cylinder line 30, the bucket lifting and breaking out of the pile of material. As soon as the pressure within the line 30 drops, the valve 41 will close, interrupting the circuit to control valve 29 and causing the curling of the bucket to cease.

RAISE TO DUMP POSITION After the bucket has been loaded as described in the cycle above, the sequential valve 36 is moved to the next adjacent position to actuate the raise to dump circuit. This circuit includes a line 47 extending from the sequential valve 36 to a cam-controlled valve 49. The circuit through the valve 49 is normally open and extends through the line 50 to the lift cylinder control valve 27 to operate that valve in a direction to raise the boom and bucket. Upon the boom having been raised to a position adjacent its upper limit of travel, a cam 51 actuates the valve 49 to close the circuit to the control valve 27 and limit raising movement of the boom. Preferebaly, the cam 51 is carried on the rear end of the boom at the pivotal mounting of the boom on the frame portion 11 (see FIGURE 6).

The line 47 also extends to a bucket leveling control valve 54 from which a line 55 leads to a switching valve 56. The switching valve 56 is connected with the bucket control valve 29 by line 5-7, pressure in the line 57 serving to operate the valve 29 in a direction to move the bucket in a direction towards dump position in order to prevent overtilting of the bucket as the boom is raised. The switching valve 56 is normally positioned to connect the line '57 with the circuit for placing the bucket in dump position, as will be described, but pressure in the line 55 actuates the valve 56 to connect the line 57 with the bucket attitude control circuit. Operation of the valve 54 is controlled by a cam 53 actuated by a cable 58 secured to the bucket 17 to rotate the cam in response to bucket position.

DUMP POSITION The Dump Position control circuit comprises a line 59 connected with the sequential valve 36 in the position next following the line 47. The line 59 leads to a bucket dump control valve 60 which is normally open and is connected by line 61 to the switching valve 56. Pressure within the line 59 pressurizes the line 57 to operate the valve 29 and swing the bucket 17 to dump position. Upon the bucket reaching dump position, a cam 62 operated by cable 58 extending to the bucket closes the valve 60. Inasmuch as the boom 12 previously has been raised to fully raised position in the Raise to Dump control circuit, dumping into a truck or spoil pile is accomplished.

RETURN TO LOAD POSITION A line '65 extends from the sequential valve 36 next following line 59 and controls the Return to Load Position control circuit. The line 65 extends to a control valve 66 which is normally connected with a line 67 extending to the bucket curl control valve 44. Pressure in the line 67 actuates the valve 44 to connect the line 67 with the line 45 and operate the bucket cylinder control valve 29 in a direction to curl the bucket 17. As the bucket 17 moves from dump position, the cam 69 is rotated by cable 58 to actuate valve 66 and interrupt the connection of the line 65 with the line 67 and stop further curling of the bucket. The cam 69 is positioned to stop curling of the bucket when the bottom wall 19* of the bucket has reached such a position relative to the loader boom 12 that when the loader boom is lowered to place the bucket at ground level, the bottom wall of the bucket will be parallel to the ground.

Switching of the control valve 66 connects the line 65 with the line 70 leading to a cam controlled valve 71. The valve 71 is controlled by cam 72 fixed to the rear of the boom for operating the valve against its bias when the boom is at proper height so that the lower wall of the bucket is at ground elevation for reloading the bucket. The valve 71 controls operation of a detented valve 74 which in turn is connected by line 75 to the lift cylinder control valve 27. The valve 71 controls only operation of the valve 74.

The valve 74 is supplied with fluid under pressure by a line 76 leading directly from line 65 and supplying to the valve 74 pressurized fluid for operating the lift cylinder control valve 27. A branch line 77 from the line 76 extends to the valve 71 to operate the valve 74 so as to cut off operation of valve 27 when the boom has been dropped to bucket loading position.

The sequential valve 3 6, which preferably is provided with a suitable handle for a step by-step operation of the valve may be cycled by continued rotary movement in the same direction to initiate a new cycle of load and dump. The sole purpose of the valve 36 is to energize each of the lines 40, 47, 59 and 65 in succession a channel 79 within the valve serving to vent to sump all but the line pressurized by the pressure passage 80 of the sequential valve.

The system that has been described is a manually controlled system in which the step-by-step sequential valve 36 is manually operated, and operation of the loader is independent of operation of the driving line to the wheels of the tractor 10. This invention also contemplates modulating the action of the control circuit for Load Position so as to operate the lift cylinder control valve 27 and raise the boom upon torque in the drive line of the tractor reaching a predetermined amount as the bucket is driven into the pile of material to be loaded.

FIGURE 4 shows schematically a tractor drive system of the infinitely variable hydrostatic type in which the tractor engine 81, which also is used to drive the pump 25, drives a variable displacement hydraulic pump 82 which in turn is connected by discharge and return lines 84 and'85 to a variable displacement hydraulic motor 86 connected with the final drive of the tractor. A line 87 connected with the discharge line 84 extends downwardly to operate a detented valve 89 connected with the line 40. The valve 89 is operated by pressure in the line 87, which is proportional to torque developed in the hydrostatic drive of the tractor, reaching a predetermined amount. The valve 89 senses direct pressure from the line 40 through the line 90 and through the valve 89 and line 91 to a pressure operated valve 92. Pressure in the line 91 not only serves to operate the valve 92 against its bias, but also to pressurize the line 50 leading to the lift cylinder control valve 27 to operate this valve in a direction to raise the boom and bucket.

The arrangement is such that as the torque in the tractor drive reaches a predetermined amount, pressure through the line 87 will operate the valve 89 to cause pressure from the line 40 to operate the lift cylinder control valve 27 and cause lifting of the boom to break the bucket out of the pile of material and initiate lifting of the bucket.

We claim:

1. In a tractor front mounted loader having a boom mounted on the tractor for vertical swinging movement, a bucket mounted on the forward end of the boom for vertical swinging movement, hydraulic means including a hydraulic lift cylinder for raising the boom and a hydraulic bucket cylinder for vertically swinging the bucket relative to the boom, a lift cylinder control valve, a bucket cylinder control valve; a hydraulic control circuit, including a step-by-step sequential valve, for pressurizing in succession a plurality of hydraulic control circuits for actuating the lift cylinder control valve and bucket cylinder control valve, comprising a first control circuit controlling actuation of the lift cylinder control valve :to lift the boom to dump height, a second control circuit controlling the bucket cylinder control valve to move the bucket cylinder to bucket dump position and a third control circuit controlling lowering of the boom and raising of the bucket to restore the loader to load position.

2. In a tractor front mounted loader as claimed in claim 1, the first control circuit having means for maintaining the bucket at generally constant attitude during lifting of the boom.

3. A tractor front mounted loader as claimed in claim 1 in combination with a tractor having a drive line for propelling the tractor and means for sensing the torque in said drive line, and means responsive to said torque exceeding a predetermined amount for actuating the first control circuit to initiate lifting of the boom.

4. A tractor front mounted loader and tractor as claimed in claim 3, in which the tractor drive line includes a hydrostatic transmission comprising an interconnected hydraulc pump and hydraulic motor and pressure on the discharge side of the pump is utilized to operate a valve in the first control circuit to initiate lifting of the boom.

References Cited UNITED STATES PATENTS 3,339,763 9/1967 Caywood et al. 2l4-l38 3,348,709 10/1967 Fauchere 2l4--l38 FOREIGN PATENTS 129,831 11/ 1948 Australia.

HUGO O. SCHULZ, Primary Examiner 

